Improvement in sun-dials



'M. WHEELER.

SUN-DIALS.

Fig.1

iNVENTUK:

WITNEESEE= ILPEI'ERS, PHOTO-UTNQGRAPHER. WASNINGTON, D. C.

ITED STATES PATENT QFFICE.

MARSHAL WHEELER, OF GRAND RAPIDS, MICHIGAN.

IMPROVEMENT IN SUN-DIALS.

Specification forming part of Letters Patent No. 177,305, dated May 9,1876; application filed April 17, 1876.

To all whom it may concern:

Be it known that I, MARSHAL WHEELER, of Grand Rapids, in the county ofKent and State of Michigan, have invented certain new and usefulImprovements in Solar Qhronometer; and I do hereby declare the followingto be a full, clear, and exact description of the invention, such aswill enable others skilled in the art to which it pertains to makeanduse it, reference being had to the accompanying drawings, which formpart of this specifica tion.

My invention relates to an improvement in solar .chronometers; and itconsists in the arrangement and combination of devices that will be-morefully described hereinafter, whereby the instrument is made moreaccurate, and the easier to read.

The accompanying drawings represent my invention. v

a represents a suitable triangular frame or base, which is supportedupon and adjusted by the screw-feet b. Passing down through this frameis the shaft 0, upon which the whole instrument proper freely turns.Passing around this shaft is an adjusting-plate, d, that is providedwith screws 0, for adjust ing it back and forth, and ascrewJ', forClamping it rigidly to the shaft. Secured to the top of this shaft is along plate, 9, upon which are placed two levels, h, at right angles toeach other, so as to show when the plate is per-. fectly level. Upon theextreme ends of this plate are placed the standards i, upon which thejournals of the semicircle j rest. I These journals are held in suitableboxes, so that the semicircle can turn freely througha portion of acircle, and thus accommodate itself to the rolling motion of a ship.

By thus suspending the semicircle from its center of gravity, instead ofpivoting it at its lower edge, and attaching the graduated arc lto oneof the journals, so that the arc and semicircle will move together,latitude can be readfrom the are instead of a horizontal bar.

are made at equidistant spaces, rendering the construction of a Verniereasy to read to any desired fraction of a degree.

The semicircle j, instead of being made straight in cross-section, orthe segment of a cylinder, is made on a true curve, or the segment of ahemisphere, whereby all the lines drawn on its surface can be placed atequidistant spaces apart. 'Where'the surface is flat, as in thoseheretofore made, these lines cannot be placed equidistant, and hence itis diflicult to use a Vernier in reading the suns declination. In thecenter of the top plate 0 is pivoted the revolving solar plate a,through which is made a minute-hole, through which the sunlight passes,and falls upon the curved surface of semicircle. In this hole there may.of light on any part of the semicircle, giving a full round image ofthe sun at all hours of the day between 6' a. m. and 6 ,p. m.

Having thus described my invention, 1 claim- 1. The semicircle j, havingits surface made on a curve, so as to form the segmentof a hemisphere,substantially as shown.

2. The revolving solar plate, in combination with the semicircle,substantially as specified.

3. In a solar chronometer, the combination of a pivot, 0, plate g,standard I, semicircle j, havingjournals upon its ends, graduated arc,and revolving solar plate, substantially as shown and described.

In testimony that I claim the foregoing I have hereunto set my hand andsealthis 6th day of April, 1876.

MARSHAL WHEELER. [L. 8.]

Witnesses:

JOHN M. BUTLER, A. G. STEINER.

